Cells throughout the human body are constantly being damaged as a part of natural life, normal cellular processes, UV and chemical exposure and environmental factors — resulting in what are called DNA double-strand breaks. Thankfully, to prevent the accumulation of DNA damage that could eventually lead to cell dysfunction, cancer or death, the healthy human body has developed ways of locating and repairing the damage.
Unfortunately, these DNA repair mechanisms themselves are not impervious to genetic errors. Genetic mutations that disrupt DNA repair can contribute to devastating disease.
Across the early-stage progenitor cells that give rise to the human brain’s 80 billion neuronal cells, genomic alterations impacting DNA repair processes have been linked to neuropsychiatric disorders and the childhood brain cancer medulloblastoma. But until now, it was not known exactly which disruptions in DNA repair were involved.
For almost a century, brain tumors have been diagnosed based on their appearance under a microscope and classified by their resemblance to the brain cells from which they are derived. For example, astrocytoma ends with “-oma” to designate that it is a tumor derived from astrocytes. In some cases, especially in children, brain tumors resemble cells in the developing brain and are named for the cells from which they are presumed to arise, such as pineoblastoma for developing cells within the pineal gland or medulloblastoma for developing cells within the cerebellum or brainstem.
When you look at an apple, no matter what variety, on the surface you can be pretty sure it’s actually an apple. From there, you can make lots of assumptions about it, like how it will taste when you bite into it and what will happen if you plant the seeds in your yard.
With cancer, we can’t make those kinds of assumptions. While two tumors from the same location in two patients may look the same, doctors and researchers have come to recognize that their behavior and the mutations driving them can be radically different, as can their response to therapy.
With that recognition, physician/scientists like Scott Pomeroy, MD, PhD, the neurologist-in-chief at Boston Children’s Hospital, are taking a deeper look at the tumors they commonly see and asking whether what on the surface looks like one kind of tumor might actually be something completely different. Pomeroy in particular has applied this view to one of the biggest questions in pediatric cancer: Why do medulloblastomas, the most common malignant childhood brain tumor, behave so differently from child to child? …
A urine sample can tell you many things. It can reveal pregnancy, signal an infection or unmask drug use. Could it also tell you about brain tumors? Maybe.
Current image-based screening for brain tumors and other neurologic diseases is time-consuming, costly and poses some risk—especially for young children who must be sedated to hold still in the scanner. The ordeal is multiplied for children who have had brain surgery and need frequent checks for disease resurgence — especially if they don’t live close to pediatric neuroimaging facilities. …
Diversity is good in populations of people, but when it comes to cancer, it’s bad news. In the case of medulloblastoma—the most common malignant brain cancer in children—tumor diversity has been one of the greatest barriers to designing effective treatments.
Now, in the largest genomic study of human medulloblastomas ever, Children’s researchers and their collaborators have subdivided the cancer into six different diseases—each with distinct molecular “fingerprints.” Knowledge of these tumor subtypes will improve neurologists’ ability to direct and individualize treatment. One subtype, carrying the worst prognosis, had never before been characterized. …